Use the new relay_has_address_set() interface when deciding if we need to
fetch directory information from an authority as a relay.

If no IPv4 address is found, we'll proceed with a fetch so we can learn our
address in the HTTP header or NETINFO cell that a trusted authority will send
us back.

Related to #40025

Signed-off-by: David Goulet <dgoulet@torproject.org>